I have a 1999 chevrolet camaro with the vortec v6 3800 series, what is the oil...

[shiznizzal24]

...blend? 5w-30? 10w-30? It has about 89000 miles on it, what is the best oil that improves the maximum life? Also at what time should i switch to high mileage oil? What is the best oil for the job?

[truly speaking]

it may be best to use the 10w30 if you have that many miles on it. Your engine has alot of bearings and such that will need to stay lubed and using a thicker oil like the 10w30 will really help. at 89000 miles 5w30 would be like water. as far as the best oil i would have to say Castrol GTX.

[coaltruck344]

Engine oil viscosity (thickness) has an effect on fuel economy and cold -weather operation (starting and oil flow).
Lower viscosity engine oils can provide better fuel economy and cold-weather performance; howerer higher temperature weather conditions require higher viscosity engine oils for satisfactory lubrication.
GM recomends 10-30 W in 3.8 V6 engines
If you live in Alaska u may want 5-30 W colder enviroment